FAIR VALUE MEASUREMENTS - Schedule of Assets and Liabilities as Presented on Ciena's Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	May 02, 2026	Nov. 01, 2025
Assets:
Total assets measured at fair value	$ 1,213,731	$ 1,198,881
Liabilities:
Total liabilities measured at fair value	32,281	7,659
Level 1
Assets:
Total assets measured at fair value	841,090	927,807
Liabilities:
Total liabilities measured at fair value	25,588	0
Level 2
Assets:
Total assets measured at fair value	372,641	271,074
Liabilities:
Total liabilities measured at fair value	6,693	7,659
Level 3
Assets:
Total assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	0	0
Balance Sheet Location [Axis]: us-gaap:AccruedLiabilitiesCurrent
Liabilities:
Accrued liabilities and other short-term obligations	6,693	6,314
Balance Sheet Location [Axis]: us-gaap:AccruedLiabilitiesCurrent \| Level 1
Liabilities:
Accrued liabilities and other short-term obligations	0	0
Balance Sheet Location [Axis]: us-gaap:AccruedLiabilitiesCurrent \| Level 2
Liabilities:
Accrued liabilities and other short-term obligations	6,693	6,314
Balance Sheet Location [Axis]: us-gaap:AccruedLiabilitiesCurrent \| Level 3
Liabilities:
Accrued liabilities and other short-term obligations	0	0
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue
Assets:
Cash equivalents	813,802	901,176
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Level 1
Assets:
Cash equivalents	810,409	901,077
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Level 2
Assets:
Cash equivalents	3,393	99
Balance Sheet Location [Axis]: us-gaap:CashAndCashEquivalentsAtCarryingValue \| Level 3
Assets:
Cash equivalents	0	0
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesNoncurrent
Assets:
Long-term investments	200,106	57,142
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesNoncurrent \| Level 1
Assets:
Long-term investments	0	0
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesNoncurrent \| Level 2
Assets:
Long-term investments	200,106	57,142
Balance Sheet Location [Axis]: us-gaap:MarketableSecuritiesNoncurrent \| Level 3
Assets:
Long-term investments	0	0
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent
Assets:
Other assets	29,683	21,179
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Level 1
Assets:
Other assets	25,443	21,179
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Level 2
Assets:
Other assets	4,240	0
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent \| Level 3
Assets:
Other assets	0	0
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Liabilities:
Other long-term obligations	25,588	1,345
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent \| Level 1
Liabilities:
Other long-term obligations	25,588	0
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent \| Level 2
Liabilities:
Other long-term obligations	0	1,345
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent \| Level 3
Liabilities:
Other long-term obligations	0	0
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent
Assets:
Other assets	12,432	3,236
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Level 1
Assets:
Other assets	0	0
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Level 2
Assets:
Other assets	12,432	3,236
Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent \| Level 3
Assets:
Other assets	0	0
Balance Sheet Location [Axis]: us-gaap:ShortTermInvestments
Assets:
Short-term investments	157,708	216,148
Balance Sheet Location [Axis]: us-gaap:ShortTermInvestments \| Level 1
Assets:
Short-term investments	5,238	5,551
Balance Sheet Location [Axis]: us-gaap:ShortTermInvestments \| Level 2
Assets:
Short-term investments	152,470	210,597
Balance Sheet Location [Axis]: us-gaap:ShortTermInvestments \| Level 3
Assets:
Short-term investments	$ 0	$ 0